UPC1555 Datasheet, PDF (6/12 Pages) NEC – TIMER CIRCUIT

µPC1555
PIN FUNCTIONS
1. Trigger pin (pin 2) :
2. Output pin (pin 3)
:
3. Reset pin (pin 4)
:
4. Control voltage (pin 5) :
5. Threshold pin (pin 6) :
6. Discharge pin (pin 7) :
Supplying one-third of VCC to the trigger pin triggers the circuit, changing the output
voltage from low to high.
The maximum output current is 200 mA. Be careful not to exceed the total loss (see
the PT-TA characteristic curve).
Supplying 0.4 V or less to the reset pin stops the circuit operation (such as monostable
or astable multivibrator operation).
When not used, the reset pin should be clamped at 1 V to VCC.
This voltage determines the threshold level of the comparator. It is set to two-thirds
of VCC. It is possible to configure a PWM (pulse width modulation) or PPM (pulse
position modulation) mode application circuit by supplying a control voltage from the
outside. When this pin is not in use, it should be bypassed using a capacitor of
approximately 0.01 µF for more table circuit operation.
The values of an external capacitor (C) and resistor (R) connected to this pin determine
the width of the output pulse.
This pin is used to discharge an external capacitor (if connected). It operates, when
the internal flip-flop circuit is turned on, or a reset signal is applied.
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